Importance of copper minerals 
http://www.suanpan.go.th/webboard/index.php?action=profile;u=123 
 
What Is Copper? 
http://siatkachorzow.phorum.pl/viewtopic.php?p=65734#65734 
 
 
What causes copper's emissions? 
http://tsxvresearch.com/forum/viewtopic.php?f=2&amp;t=57012 
 
Copper and its compounds 
http://rpg.six168.com/viewthread.php?tid=34113&amp;page=1&amp;authorid=56503 
 
Copper: An Ancient Metal 
http://n1sa.com/forum.php?mod=viewthread&amp;tid=7383821&amp;extra= 
 
Top Five Copper Producing Countries 
http://stock-tree.com/forum/viewtopic.php?t=833